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JIDE Common Layer (Professional Swing Components)
/*
* @(#)FastGradientPainter.java 12/12/2004
*
* Copyright 2002 - 2005 JIDE Software Inc. All rights reserved.
*/
package com.jidesoft.swing;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
class FastGradientPainter {
private static GradientCache gradientCache = new GradientCache();
//no instantiation
private FastGradientPainter() {
}
/**
* Draws a rectangular gradient in a vertical or horizontal direction.
* The drawing operations are hardware optimized whenever possible using the
* Java2D hardware rendering facilities. The result is gradient rendering
* approaching the performance of flat color rendering.
*
* @param g2 Graphics2D instance to use for rendering
* @param s shape confines of gradient
* @param startColor starting color for gradient
* @param endColor ending color fro gradient
* @param isVertical specifies a vertical or horizontal gradient
*/
public static void drawGradient(Graphics2D g2, Shape s, Color startColor, Color endColor, boolean isVertical) {
Rectangle r = s.getBounds();
if (r.height <= 0 || r.width <= 0) return;
int length = isVertical ? r.height : r.width;
GradientInfo info = new GradientInfo(g2.getDeviceConfiguration(), length, startColor, endColor, isVertical);
BufferedImage gradient = gradientCache.retrieve(info);
if (gradient == null) {
gradient = createGradientTile(info);
gradientCache.store(info, gradient);
}
Shape prevClip = null;
boolean nonRectangular = false;
if (!r.equals(s)) {
nonRectangular = true;
prevClip = g2.getClip();
g2.clip(s);
}
if (isVertical) {
int w = gradient.getWidth();
int loops = r.width / w;
for (int i = 0; i < loops; i++)
g2.drawImage(gradient, r.x + i * w, r.y, null);
int rem = r.width % w;
if (rem > 0) {
g2.drawImage(gradient, r.x + loops * w, r.y, r.x + loops * w + rem, r.y + length, 0, 0, rem, length, null);
}
}
else {
int h = gradient.getHeight();
int loops = r.height / h;
for (int i = 0; i < loops; i++)
g2.drawImage(gradient, r.x, r.y + i * h, null);
int rem = r.height % h;
if (rem > 0) {
g2.drawImage(gradient, r.x, r.y + loops * h, r.x + length, r.y + loops * h + rem, 0, 0, length, rem, null);
}
}
if (nonRectangular) {
g2.setClip(prevClip);
}
}
private static BufferedImage createGradientTile(GradientInfo info) {
boolean t = info.startColor.getTransparency() > 1 || info.endColor.getTransparency() > 1;
int dx, dy, w, h;
if (info.isVertical) {
dx = 0;
h = dy = info.length;
w = 32;
}
else {
w = dx = info.length;
dy = 0;
h = 32;
}
BufferedImage img = info.gfxConfig.createCompatibleImage(w, h, t ? Transparency.TRANSLUCENT : Transparency.OPAQUE);
Paint gp = new GradientPaint(0, 0, info.startColor, dx, dy, info.endColor);
Graphics2D g = img.createGraphics();
g.setPaint(gp);
g.fillRect(0, 0, w, h);
g.dispose();
return img;
}
}
/**
* Containts all information pertaining to a particular gradient.
*/
class GradientInfo {
GraphicsConfiguration gfxConfig;
int length;
Color startColor, endColor;
boolean isVertical;
public GradientInfo(GraphicsConfiguration gc, int ln, Color sc, Color ec, boolean v) {
gfxConfig = gc;
length = ln;
startColor = sc;
endColor = ec;
isVertical = v;
}
boolean isEquivalent(GradientInfo gi) {
return (gi.gfxConfig.equals(gfxConfig) && gi.length == length && gi.startColor.equals(startColor) && gi.endColor.equals(endColor) && gi.isVertical == isVertical);
}
@Override
public boolean equals(Object o) {
if (!(o instanceof GradientInfo)) return false;
return isEquivalent((GradientInfo) o);
}
@Override
public String toString() {
return "Direction:" + (isVertical ? "ver" : "hor") + ", Length: " + Integer.toString(length) + ", Color1: " + Integer.toString(startColor.getRGB(), 16) + ", Color2: " + Integer.toString(endColor.getRGB(), 16);
}
}
/**
* A cache utilizing SoftReferences under the hood for memory efficient handling
* of gradients.
*/
class GradientCache {
private GradientCacheEntry[] gradients;
private int size;
private int threshold;
private final float loadFactor;
private final ReferenceQueue queue = new ReferenceQueue();
GradientCache() {
this.loadFactor = 0.75f;
threshold = 16;
gradients = new GradientCacheEntry[16];
}
BufferedImage retrieve(GradientInfo info) {
int ln = info.length;
GradientCacheEntry[] grads = getGradients();
int index = bucket(ln, grads.length);
GradientCacheEntry e = grads[index];
while (e != null) {
GradientInfo egi = e.getInfo();
try {
if (egi != null) {
if (e.length == ln && egi.isEquivalent(info)) {
return e.gradient;
}
}
}
catch (NullPointerException npe) {
// apparently egi will or e will be cleared anyways sometimes,
// so we have to catch a possible NPE
// I print the values to get a better understanding of the situation.
// comment this if unacceptable or change to use logging if needed
// System.err.println("e = " + e);
// System.err.println("egi = " + egi);
}
e = e.next;
}
return null;
}
Object store(GradientInfo info, BufferedImage gradient) {
GradientCacheEntry[] grads = getGradients();
int i = bucket(info.length, grads.length);
GradientCacheEntry e = grads[i];
if (!entryNotInCache(e, info)) {
System.err.println("Duplicate entry found!");
}
grads[i] = new GradientCacheEntry(info, gradient, queue, e);
if (++size >= threshold)
resize(grads.length << 1);
return null;
}
private boolean entryNotInCache(GradientCacheEntry e, GradientInfo info) {
while (e != null && e.getInfo() != null) { // to fix a NPE
if (e.length == info.length && e.getInfo().isEquivalent(info)) {
return false;
}
e = e.next;
}
return true;
}
private void resize(int newCapacity) {
GradientCacheEntry[] oldArray = getGradients();
int oldCapacity = oldArray.length;
if (oldCapacity == ((Integer.MAX_VALUE >> 1) + 1)) {
threshold = Integer.MAX_VALUE;
return;
}
GradientCacheEntry[] newArray = new GradientCacheEntry[newCapacity];
moveEntries(oldArray, newArray);
gradients = newArray;
if (size >= (threshold >> 1)) {
threshold = (int) (newCapacity * loadFactor);
}
else {
cleanOldCacheEntries();
moveEntries(newArray, oldArray);
gradients = oldArray;
}
}
private GradientCacheEntry[] getGradients() {
cleanOldCacheEntries();
return gradients;
}
private static int bucket(int h, int length) {
return h & (length - 1);
}
private void moveEntries(GradientCacheEntry[] src, GradientCacheEntry[] dest) {
for (int j = 0; j < src.length; ++j) {
GradientCacheEntry e = src[j];
src[j] = null;
while (e != null) {
GradientCacheEntry next = e.next;
Object o = e.get();
if (o == null) {
e.next = null;
e.gradient = null;
size--;
}
else {
int i = bucket(e.length, dest.length);
e.next = dest[i];
dest[i] = e;
}
e = next;
}
}
}
private void cleanOldCacheEntries() {
GradientCacheEntry e;
while ((e = (GradientCacheEntry) queue.poll()) != null) {
int i = bucket(e.length, gradients.length);
GradientCacheEntry prev = gradients[i];
GradientCacheEntry p = prev;
while (p != null) {
GradientCacheEntry next = p.next;
if (p == e) {
if (prev == e)
gradients[i] = next;
else
prev.next = next;
e.next = null;
e.gradient = null;
size--;
break;
}
prev = p;
p = next;
}
}
}
}
class GradientCacheEntry extends SoftReference {
GradientCacheEntry next;
BufferedImage gradient;
int length;
GradientCacheEntry(GradientInfo info, BufferedImage gradient, ReferenceQueue queue, GradientCacheEntry next) {
super(info, queue);
this.next = next;
this.gradient = gradient;
length = info.length;
}
GradientInfo getInfo() {
return (GradientInfo) get();
}
BufferedImage getGradient() {
return gradient;
}
}
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